{"abstract":"In years starting on Friday, Saturday or Sunday every week number is one week early.","category":"Calendar recurrence rules","checks":7,"contract":"FREQ=YEARLY with BYWEEKNO (ISO weeks, Monday start, week 1 contains January 4) and BYDAY weekdays (0=Monday). Negative week numbers count from the last ISO week of the year (-1 is the last). A year has 53 weeks exactly when December 28 falls in week 53; week numbers outside 1..weeks are ignored for that year. Dates may fall in the adjacent calendar year. Expand years year_start .. year_start+years-1 and return unique ISO dates sorted.","evaluation_group":"w2-calendar-recurrence-rules-yearly-byweekno","failed_approach":"The partial repair `jan4 - dt.timedelta(days=(jan4.weekday() + 1) % 7)` aligns weeks to Sunday instead of Monday.","family":"w2-calendar-recurrence-rules-yearly-byweekno-week-one-monday","id":"FA-77111","implementations":{"attempt":{"sha256":"09a78635f52790696d0b891db878a82b87b7fbe7ce3a4b10cc406359c3aba309","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport datetime as dt\nimport calendar\nN = 1\nobservations = []\ndef solve(year_start, weeknos, weekdays, years):\n    out = set()\n    for y in range(year_start, year_start + years):\n        jan4 = dt.date(y, 1, 4)\n        week1 = jan4 - dt.timedelta(days=(jan4.weekday() + 1) % 7)\n        nweeks = dt.date(y, 12, 28).isocalendar()[1]\n        for wn in weeknos:\n            w = wn if wn > 0 else nweeks + wn + 1\n            if not (1 <= w <= nweeks):\n                continue\n            for wd in weekdays:\n                out.add(week1 + dt.timedelta(days=(w - 1) * 7 + wd))\n    return sorted(d.isoformat() for d in out)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression: week 1 in 2021', [2021, [1], [0], 1], ['2021-01-04']),\n  ('week 53 existence', [2019, [53], [0], 3], ['2020-12-28']),\n  ('last week negative', [2020, [-1], [6], 3], ['2021-01-03', '2022-01-02', '2023-01-01']),\n  ('leap year starting wednesday', [2024, [-1, 53], [0], 2], ['2024-12-23', '2025-12-22']),\n  ('week 20 monday friday',\n   [2023, [20], [0, 4], 2],\n   ['2023-05-15', '2023-05-19', '2024-05-13', '2024-05-17']),\n  ('too-negative week', [2021, [-60, 2], [2], 1], ['2021-01-13']),\n  ('week 1 sunday spans years',\n   [2015, [1, 52], [6], 2],\n   ['2015-01-04', '2015-12-27', '2016-01-10', '2017-01-01'])],\n [('last week negative', [2020, [-1], [6], 3], ['2021-01-03', '2022-01-02', '2023-01-01']),\n  ('leap year starting wednesday', [2024, [-1, 53], [0], 2], ['2024-12-23', '2025-12-22']),\n  ('week 20 monday friday',\n   [2023, [20], [0, 4], 2],\n   ['2023-05-15', '2023-05-19', '2024-05-13', '2024-05-17']),\n  ('too-negative week', [2021, [-60, 2], [2], 1], ['2021-01-13']),\n  ('week 1 sunday spans years',\n   [2015, [1, 52], [6], 2],\n   ['2015-01-04', '2015-12-27', '2016-01-10', '2017-01-01']),\n  ('second to last week', [2026, [-2], [3], 2], ['2026-12-24', '2027-12-23']),\n  ('many weeks', [2027, [1, -1, 26], [0], 1], ['2027-01-04', '2027-06-28', '2027-12-27'])],\n [('week 20 monday friday',\n   [2023, [20], [0, 4], 2],\n   ['2023-05-15', '2023-05-19', '2024-05-13', '2024-05-17']),\n  ('too-negative week', [2021, [-60, 2], [2], 1], ['2021-01-13']),\n  ('week 1 sunday spans years',\n   [2015, [1, 52], [6], 2],\n   ['2015-01-04', '2015-12-27', '2016-01-10', '2017-01-01']),\n  ('second to last week', [2026, [-2], [3], 2], ['2026-12-24', '2027-12-23']),\n  ('many weeks', [2027, [1, -1, 26], [0], 1], ['2027-01-04', '2027-06-28', '2027-12-27']),\n  ('year starting saturday', [2022, [1, 53], [1, 5], 1], ['2022-01-04', '2022-01-08']),\n  ('53 in 2026', [2026, [53], [4], 1], ['2027-01-01'])],\n [('week 1 sunday spans years',\n   [2015, [1, 52], [6], 2],\n   ['2015-01-04', '2015-12-27', '2016-01-10', '2017-01-01']),\n  ('second to last week', [2026, [-2], [3], 2], ['2026-12-24', '2027-12-23']),\n  ('many weeks', [2027, [1, -1, 26], [0], 1], ['2027-01-04', '2027-06-28', '2027-12-27']),\n  ('year starting saturday', [2022, [1, 53], [1, 5], 1], ['2022-01-04', '2022-01-08']),\n  ('53 in 2026', [2026, [53], [4], 1], ['2027-01-01']),\n  ('regression: week 1 in 2021', [2021, [1], [0], 1], ['2021-01-04']),\n  ('week 53 existence', [2019, [53], [0], 3], ['2020-12-28'])],\n [('many weeks', [2027, [1, -1, 26], [0], 1], ['2027-01-04', '2027-06-28', '2027-12-27']),\n  ('year starting saturday', [2022, [1, 53], [1, 5], 1], ['2022-01-04', '2022-01-08']),\n  ('53 in 2026', [2026, [53], [4], 1], ['2027-01-01']),\n  ('regression: week 1 in 2021', [2021, [1], [0], 1], ['2021-01-04']),\n  ('week 53 existence', [2019, [53], [0], 3], ['2020-12-28']),\n  ('last week negative', [2020, [-1], [6], 3], ['2021-01-03', '2022-01-02', '2023-01-01']),\n  ('leap year starting wednesday', [2024, [-1, 53], [0], 2], ['2024-12-23', '2025-12-22'])]]\nfor label, args, expected in fixtures[N-1]:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"broken":{"sha256":"60270fef1cd72d43119e744e79c821095530e4a971af6eb6511da6e41fe3235e","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport datetime as dt\nimport calendar\nN = 1\nobservations = []\ndef solve(year_start, weeknos, weekdays, years):\n    out = set()\n    for y in range(year_start, year_start + years):\n        jan4 = dt.date(y, 1, 4)\n        week1 = dt.date(y, 1, 1) - dt.timedelta(days=dt.date(y, 1, 1).weekday())\n        nweeks = dt.date(y, 12, 28).isocalendar()[1]\n        for wn in weeknos:\n            w = wn if wn > 0 else nweeks + wn + 1\n            if not (1 <= w <= nweeks):\n                continue\n            for wd in weekdays:\n                out.add(week1 + dt.timedelta(days=(w - 1) * 7 + wd))\n    return sorted(d.isoformat() for d in out)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression: week 1 in 2021', [2021, [1], [0], 1], ['2021-01-04']),\n  ('week 53 existence', [2019, [53], [0], 3], ['2020-12-28']),\n  ('last week negative', [2020, [-1], [6], 3], ['2021-01-03', '2022-01-02', '2023-01-01']),\n  ('leap year starting wednesday', [2024, [-1, 53], [0], 2], ['2024-12-23', '2025-12-22']),\n  ('week 20 monday friday',\n   [2023, [20], [0, 4], 2],\n   ['2023-05-15', '2023-05-19', '2024-05-13', '2024-05-17']),\n  ('too-negative week', [2021, [-60, 2], [2], 1], ['2021-01-13']),\n  ('week 1 sunday spans years',\n   [2015, [1, 52], [6], 2],\n   ['2015-01-04', '2015-12-27', '2016-01-10', '2017-01-01'])],\n [('last week negative', [2020, [-1], [6], 3], ['2021-01-03', '2022-01-02', '2023-01-01']),\n  ('leap year starting wednesday', [2024, [-1, 53], [0], 2], ['2024-12-23', '2025-12-22']),\n  ('week 20 monday friday',\n   [2023, [20], [0, 4], 2],\n   ['2023-05-15', '2023-05-19', '2024-05-13', '2024-05-17']),\n  ('too-negative week', [2021, [-60, 2], [2], 1], ['2021-01-13']),\n  ('week 1 sunday spans years',\n   [2015, [1, 52], [6], 2],\n   ['2015-01-04', '2015-12-27', '2016-01-10', '2017-01-01']),\n  ('second to last week', [2026, [-2], [3], 2], ['2026-12-24', '2027-12-23']),\n  ('many weeks', [2027, [1, -1, 26], [0], 1], ['2027-01-04', '2027-06-28', '2027-12-27'])],\n [('week 20 monday friday',\n   [2023, [20], [0, 4], 2],\n   ['2023-05-15', '2023-05-19', '2024-05-13', '2024-05-17']),\n  ('too-negative week', [2021, [-60, 2], [2], 1], ['2021-01-13']),\n  ('week 1 sunday spans years',\n   [2015, [1, 52], [6], 2],\n   ['2015-01-04', '2015-12-27', '2016-01-10', '2017-01-01']),\n  ('second to last week', [2026, [-2], [3], 2], ['2026-12-24', '2027-12-23']),\n  ('many weeks', [2027, [1, -1, 26], [0], 1], ['2027-01-04', '2027-06-28', '2027-12-27']),\n  ('year starting saturday', [2022, [1, 53], [1, 5], 1], ['2022-01-04', '2022-01-08']),\n  ('53 in 2026', [2026, [53], [4], 1], ['2027-01-01'])],\n [('week 1 sunday spans years',\n   [2015, [1, 52], [6], 2],\n   ['2015-01-04', '2015-12-27', '2016-01-10', '2017-01-01']),\n  ('second to last week', [2026, [-2], [3], 2], ['2026-12-24', '2027-12-23']),\n  ('many weeks', [2027, [1, -1, 26], [0], 1], ['2027-01-04', '2027-06-28', '2027-12-27']),\n  ('year starting saturday', [2022, [1, 53], [1, 5], 1], ['2022-01-04', '2022-01-08']),\n  ('53 in 2026', [2026, [53], [4], 1], ['2027-01-01']),\n  ('regression: week 1 in 2021', [2021, [1], [0], 1], ['2021-01-04']),\n  ('week 53 existence', [2019, [53], [0], 3], ['2020-12-28'])],\n [('many weeks', [2027, [1, -1, 26], [0], 1], ['2027-01-04', '2027-06-28', '2027-12-27']),\n  ('year starting saturday', [2022, [1, 53], [1, 5], 1], ['2022-01-04', '2022-01-08']),\n  ('53 in 2026', [2026, [53], [4], 1], ['2027-01-01']),\n  ('regression: week 1 in 2021', [2021, [1], [0], 1], ['2021-01-04']),\n  ('week 53 existence', [2019, [53], [0], 3], ['2020-12-28']),\n  ('last week negative', [2020, [-1], [6], 3], ['2021-01-03', '2022-01-02', '2023-01-01']),\n  ('leap year starting wednesday', [2024, [-1, 53], [0], 2], ['2024-12-23', '2025-12-22'])]]\nfor label, args, expected in fixtures[N-1]:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"},"fixed":{"sha256":"1bf8675221608a6eaa01e46aef10b50753f45fd6b34db88f615e16221044d69e","source":"\"\"\"Failure Map reference implementation. Python standard library only.\"\"\"\nimport json\nimport datetime as dt\nimport calendar\nN = 1\nobservations = []\ndef solve(year_start, weeknos, weekdays, years):\n    out = set()\n    for y in range(year_start, year_start + years):\n        jan4 = dt.date(y, 1, 4)\n        week1 = jan4 - dt.timedelta(days=jan4.weekday())\n        nweeks = dt.date(y, 12, 28).isocalendar()[1]\n        for wn in weeknos:\n            w = wn if wn > 0 else nweeks + wn + 1\n            if not (1 <= w <= nweeks):\n                continue\n            for wd in weekdays:\n                out.add(week1 + dt.timedelta(days=(w - 1) * 7 + wd))\n    return sorted(d.isoformat() for d in out)\ndef check(label, actual, expected):\n    observations.append({\"check\": label, \"actual\": actual, \"expected\": expected, \"passed\": actual == expected})\nfixtures = [[('regression: week 1 in 2021', [2021, [1], [0], 1], ['2021-01-04']),\n  ('week 53 existence', [2019, [53], [0], 3], ['2020-12-28']),\n  ('last week negative', [2020, [-1], [6], 3], ['2021-01-03', '2022-01-02', '2023-01-01']),\n  ('leap year starting wednesday', [2024, [-1, 53], [0], 2], ['2024-12-23', '2025-12-22']),\n  ('week 20 monday friday',\n   [2023, [20], [0, 4], 2],\n   ['2023-05-15', '2023-05-19', '2024-05-13', '2024-05-17']),\n  ('too-negative week', [2021, [-60, 2], [2], 1], ['2021-01-13']),\n  ('week 1 sunday spans years',\n   [2015, [1, 52], [6], 2],\n   ['2015-01-04', '2015-12-27', '2016-01-10', '2017-01-01'])],\n [('last week negative', [2020, [-1], [6], 3], ['2021-01-03', '2022-01-02', '2023-01-01']),\n  ('leap year starting wednesday', [2024, [-1, 53], [0], 2], ['2024-12-23', '2025-12-22']),\n  ('week 20 monday friday',\n   [2023, [20], [0, 4], 2],\n   ['2023-05-15', '2023-05-19', '2024-05-13', '2024-05-17']),\n  ('too-negative week', [2021, [-60, 2], [2], 1], ['2021-01-13']),\n  ('week 1 sunday spans years',\n   [2015, [1, 52], [6], 2],\n   ['2015-01-04', '2015-12-27', '2016-01-10', '2017-01-01']),\n  ('second to last week', [2026, [-2], [3], 2], ['2026-12-24', '2027-12-23']),\n  ('many weeks', [2027, [1, -1, 26], [0], 1], ['2027-01-04', '2027-06-28', '2027-12-27'])],\n [('week 20 monday friday',\n   [2023, [20], [0, 4], 2],\n   ['2023-05-15', '2023-05-19', '2024-05-13', '2024-05-17']),\n  ('too-negative week', [2021, [-60, 2], [2], 1], ['2021-01-13']),\n  ('week 1 sunday spans years',\n   [2015, [1, 52], [6], 2],\n   ['2015-01-04', '2015-12-27', '2016-01-10', '2017-01-01']),\n  ('second to last week', [2026, [-2], [3], 2], ['2026-12-24', '2027-12-23']),\n  ('many weeks', [2027, [1, -1, 26], [0], 1], ['2027-01-04', '2027-06-28', '2027-12-27']),\n  ('year starting saturday', [2022, [1, 53], [1, 5], 1], ['2022-01-04', '2022-01-08']),\n  ('53 in 2026', [2026, [53], [4], 1], ['2027-01-01'])],\n [('week 1 sunday spans years',\n   [2015, [1, 52], [6], 2],\n   ['2015-01-04', '2015-12-27', '2016-01-10', '2017-01-01']),\n  ('second to last week', [2026, [-2], [3], 2], ['2026-12-24', '2027-12-23']),\n  ('many weeks', [2027, [1, -1, 26], [0], 1], ['2027-01-04', '2027-06-28', '2027-12-27']),\n  ('year starting saturday', [2022, [1, 53], [1, 5], 1], ['2022-01-04', '2022-01-08']),\n  ('53 in 2026', [2026, [53], [4], 1], ['2027-01-01']),\n  ('regression: week 1 in 2021', [2021, [1], [0], 1], ['2021-01-04']),\n  ('week 53 existence', [2019, [53], [0], 3], ['2020-12-28'])],\n [('many weeks', [2027, [1, -1, 26], [0], 1], ['2027-01-04', '2027-06-28', '2027-12-27']),\n  ('year starting saturday', [2022, [1, 53], [1, 5], 1], ['2022-01-04', '2022-01-08']),\n  ('53 in 2026', [2026, [53], [4], 1], ['2027-01-01']),\n  ('regression: week 1 in 2021', [2021, [1], [0], 1], ['2021-01-04']),\n  ('week 53 existence', [2019, [53], [0], 3], ['2020-12-28']),\n  ('last week negative', [2020, [-1], [6], 3], ['2021-01-03', '2022-01-02', '2023-01-01']),\n  ('leap year starting wednesday', [2024, [-1, 53], [0], 2], ['2024-12-23', '2025-12-22'])]]\nfor label, args, expected in fixtures[N-1]:\n    check(label, solve(*args), expected)\nprint(json.dumps({\"observations\": observations, \"passed\": all(x[\"passed\"] for x in observations)}, ensure_ascii=False))\nraise SystemExit(0 if all(x[\"passed\"] for x in observations) else 1)\n"}},"limitations":"Stipulated, bounded recurrence-expansion model evaluated offline on explicit fixtures; it is not a complete iCalendar implementation and makes no claim of standards conformance. This reproducer isolates one failure mechanism. Results cover the supplied fixtures. Variants within a family share a test contract and should remain grouped when constructing evaluation splits. Related mechanisms with a shared evaluation_group must also remain together; these controlled models are not independent production incidents.","method":"Deterministic executable model with adversarial boundary fixtures.","provenance":{"created_by":"Failure Map","dependencies":"Python standard library","family":"w2-calendar-recurrence-rules-yearly-byweekno-week-one-monday","generated_at":"2026-09-29T14:49:22.544793+00:00","license":"CC0-1.0","python":"3.12.14","seed":1,"split":"open-access"},"relevance":"Recurring calendar series are expanded into concrete instances for display, reminders and conflict checks.","repair":"At the week one monday decision use `jan4 - dt.timedelta(days=jan4.weekday())`, leaving the other decision sites of the model unchanged.","root_cause":"Week 1 is taken as the week containing January 1.","sha256":"c27b5b868ddb470d2ec1ee58f0c8536f3506cdb628a9a4aa316ba7236b37d10f","title":"Yearly ISO BYWEEKNO/BYDAY expansion: week one monday · case 01","variant":1,"variant_policy":"Five numbered records share a model and may reuse boundary fixtures.","verification":{"attempt":{"elapsed_ms":40.437,"exit_code":1,"observations":[{"actual":["2021-01-03"],"check":"regression: week 1 in 2021","expected":["2021-01-04"],"passed":false},{"actual":["2020-12-27"],"check":"week 53 existence","expected":["2020-12-28"],"passed":false},{"actual":["2021-01-02","2022-01-01","2022-12-31"],"check":"last week negative","expected":["2021-01-03","2022-01-02","2023-01-01"],"passed":false},{"actual":["2024-12-22","2025-12-21"],"check":"leap year starting wednesday","expected":["2024-12-23","2025-12-22"],"passed":false},{"actual":["2023-05-14","2023-05-18","2024-05-12","2024-05-16"],"check":"week 20 monday friday","expected":["2023-05-15","2023-05-19","2024-05-13","2024-05-17"],"passed":false},{"actual":["2021-01-12"],"check":"too-negative week","expected":["2021-01-13"],"passed":false},{"actual":["2015-01-10","2016-01-02","2016-01-09","2016-12-31"],"check":"week 1 sunday spans years","expected":["2015-01-04","2015-12-27","2016-01-10","2017-01-01"],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: week 1 in 2021\", \"actual\": [\"2021-01-03\"], \"expected\": [\"2021-01-04\"], \"passed\": false}, {\"check\": \"week 53 existence\", \"actual\": [\"2020-12-27\"], \"expected\": [\"2020-12-28\"], \"passed\": false}, {\"check\": \"last week negative\", \"actual\": [\"2021-01-02\", \"2022-01-01\", \"2022-12-31\"], \"expected\": [\"2021-01-03\", \"2022-01-02\", \"2023-01-01\"], \"passed\": false}, {\"check\": \"leap year starting wednesday\", \"actual\": [\"2024-12-22\", \"2025-12-21\"], \"expected\": [\"2024-12-23\", \"2025-12-22\"], \"passed\": false}, {\"check\": \"week 20 monday friday\", \"actual\": [\"2023-05-14\", \"2023-05-18\", \"2024-05-12\", \"2024-05-16\"], \"expected\": [\"2023-05-15\", \"2023-05-19\", \"2024-05-13\", \"2024-05-17\"], \"passed\": false}, {\"check\": \"too-negative week\", \"actual\": [\"2021-01-12\"], \"expected\": [\"2021-01-13\"], \"passed\": false}, {\"check\": \"week 1 sunday spans years\", \"actual\": [\"2015-01-10\", \"2016-01-02\", \"2016-01-09\", \"2016-12-31\"], \"expected\": [\"2015-01-04\", \"2015-12-27\", \"2016-01-10\", \"2017-01-01\"], \"passed\": false}], \"passed\": false}\n"},"broken":{"elapsed_ms":41.366,"exit_code":1,"observations":[{"actual":["2020-12-28"],"check":"regression: week 1 in 2021","expected":["2021-01-04"],"passed":false},{"actual":["2020-12-28"],"check":"week 53 existence","expected":["2020-12-28"],"passed":true},{"actual":["2021-01-03","2021-12-26","2022-12-25"],"check":"last week negative","expected":["2021-01-03","2022-01-02","2023-01-01"],"passed":false},{"actual":["2024-12-23","2025-12-22"],"check":"leap year starting wednesday","expected":["2024-12-23","2025-12-22"],"passed":true},{"actual":["2023-05-08","2023-05-12","2024-05-13","2024-05-17"],"check":"week 20 monday friday","expected":["2023-05-15","2023-05-19","2024-05-13","2024-05-17"],"passed":false},{"actual":["2021-01-06"],"check":"too-negative week","expected":["2021-01-13"],"passed":false},{"actual":["2015-01-04","2015-12-27","2016-01-03","2016-12-25"],"check":"week 1 sunday spans years","expected":["2015-01-04","2015-12-27","2016-01-10","2017-01-01"],"passed":false}],"passed":false,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: week 1 in 2021\", \"actual\": [\"2020-12-28\"], \"expected\": [\"2021-01-04\"], \"passed\": false}, {\"check\": \"week 53 existence\", \"actual\": [\"2020-12-28\"], \"expected\": [\"2020-12-28\"], \"passed\": true}, {\"check\": \"last week negative\", \"actual\": [\"2021-01-03\", \"2021-12-26\", \"2022-12-25\"], \"expected\": [\"2021-01-03\", \"2022-01-02\", \"2023-01-01\"], \"passed\": false}, {\"check\": \"leap year starting wednesday\", \"actual\": [\"2024-12-23\", \"2025-12-22\"], \"expected\": [\"2024-12-23\", \"2025-12-22\"], \"passed\": true}, {\"check\": \"week 20 monday friday\", \"actual\": [\"2023-05-08\", \"2023-05-12\", \"2024-05-13\", \"2024-05-17\"], \"expected\": [\"2023-05-15\", \"2023-05-19\", \"2024-05-13\", \"2024-05-17\"], \"passed\": false}, {\"check\": \"too-negative week\", \"actual\": [\"2021-01-06\"], \"expected\": [\"2021-01-13\"], \"passed\": false}, {\"check\": \"week 1 sunday spans years\", \"actual\": [\"2015-01-04\", \"2015-12-27\", \"2016-01-03\", \"2016-12-25\"], \"expected\": [\"2015-01-04\", \"2015-12-27\", \"2016-01-10\", \"2017-01-01\"], \"passed\": false}], \"passed\": false}\n"},"fixed":{"elapsed_ms":40.175,"exit_code":0,"observations":[{"actual":["2021-01-04"],"check":"regression: week 1 in 2021","expected":["2021-01-04"],"passed":true},{"actual":["2020-12-28"],"check":"week 53 existence","expected":["2020-12-28"],"passed":true},{"actual":["2021-01-03","2022-01-02","2023-01-01"],"check":"last week negative","expected":["2021-01-03","2022-01-02","2023-01-01"],"passed":true},{"actual":["2024-12-23","2025-12-22"],"check":"leap year starting wednesday","expected":["2024-12-23","2025-12-22"],"passed":true},{"actual":["2023-05-15","2023-05-19","2024-05-13","2024-05-17"],"check":"week 20 monday friday","expected":["2023-05-15","2023-05-19","2024-05-13","2024-05-17"],"passed":true},{"actual":["2021-01-13"],"check":"too-negative week","expected":["2021-01-13"],"passed":true},{"actual":["2015-01-04","2015-12-27","2016-01-10","2017-01-01"],"check":"week 1 sunday spans years","expected":["2015-01-04","2015-12-27","2016-01-10","2017-01-01"],"passed":true}],"passed":true,"stderr":"","stdout":"{\"observations\": [{\"check\": \"regression: week 1 in 2021\", \"actual\": [\"2021-01-04\"], \"expected\": [\"2021-01-04\"], \"passed\": true}, {\"check\": \"week 53 existence\", \"actual\": [\"2020-12-28\"], \"expected\": [\"2020-12-28\"], \"passed\": true}, {\"check\": \"last week negative\", \"actual\": [\"2021-01-03\", \"2022-01-02\", \"2023-01-01\"], \"expected\": [\"2021-01-03\", \"2022-01-02\", \"2023-01-01\"], \"passed\": true}, {\"check\": \"leap year starting wednesday\", \"actual\": [\"2024-12-23\", \"2025-12-22\"], \"expected\": [\"2024-12-23\", \"2025-12-22\"], \"passed\": true}, {\"check\": \"week 20 monday friday\", \"actual\": [\"2023-05-15\", \"2023-05-19\", \"2024-05-13\", \"2024-05-17\"], \"expected\": [\"2023-05-15\", \"2023-05-19\", \"2024-05-13\", \"2024-05-17\"], \"passed\": true}, {\"check\": \"too-negative week\", \"actual\": [\"2021-01-13\"], \"expected\": [\"2021-01-13\"], \"passed\": true}, {\"check\": \"week 1 sunday spans years\", \"actual\": [\"2015-01-04\", \"2015-12-27\", \"2016-01-10\", \"2017-01-01\"], \"expected\": [\"2015-01-04\", \"2015-12-27\", \"2016-01-10\", \"2017-01-01\"], \"passed\": true}], \"passed\": true}\n"}},"verified":true,"visibility":"public"}